A widely tunable (30 nm) fiber laser based on a double Sagnac loop mirror configuration is proposed and demonstrated. A semiconductor optical amplifier (SOA) placed between the two loop mirrors acts as the gain medium. The fiber laser has two output ports with adjustable optical power outputs. Wavelength tunability is obtained through the use of a thin film tunable filter, while optical power adjustability is accomplished by proper adjustment of each of the loop mirror reflectivity via a polarization controller. A total output power of + 9 dBm is measured and the potential for higher output powers is discussed. Optical power stability of better than +/- 0.15 dB is measured for 6 hours.

We propose and demonstrate a simple dual port tunable from the C- to the L-band multi-wavelength fiber laser based on a SOA designed for C-band operation and fiber loop mirrors. The laser incorporates a polarization maintaining fiber in one of the fiber loop mirrors and delivers multi-wavelength operation at 9 laser lines with a wavelength separation of ~2.8 nm at room temperature. We show that the number of lasing wavelengths increases with the increase of the bias current of the SOA. Wavelength tunability from the C to L-band is achieved by exploiting the gain compression of a SOA. Stable multi-wavelength operation is achieved at room temperature without temperature compensation techniques, with measured power and the wavelength stability within < ±0.5 dB and 
±0.1 nm, respectively.

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We propose and demonstrate a simple compact, inexpensive, SOA-based, dual-wavelength tunable fiber laser, that can potentially be used for photoconductive mixing and generation of waves in the microwave and THz regions. A C-band semiconductor optical amplifier (SOA) is placed inside a linear cavity with two Sagnac loop mirrors at its either ends, which act as both reflectors and output ports. The selectivity of dual wavelengths and the tunability of the wavelength difference (Δλ) between them is accomplished by placing a narrow bandwidth (e.g., 0.3 nm) tunable thin film-based filter and a fiber Bragg grating (with bandwidth 0.28 nm) inside the loop mirror that operates as the output port. A total output power of + 6.9 dBm for the two wavelengths is measured and the potential for higher output powers is discussed. Optical power and wavelength stability are measured at 0.33 dB and 0.014 nm, respectively.

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We describe the mathematical model and present simulation results for the optimization of a hybrid Raman/optical parametric amplifier (HROPA), exhibiting a bandwidth of 170 nm and low ripple that covers the top half of the wavelength plan (e.g., 1441 to 1611 nm) of next generation coarse wavelength division multiplexed passive optical network systems. We show that a critical parameter in the proper amplifier parameter optimization is the inclusion of the fourth-order dispersion coefficient (β(4)). Omission of β(4) can lead to over-estimation or underestimation of the gain bandwidth, and hence its inclusion in the analysis of the HROPA is necessary.

This paper presents heterogeneously integrated bow-tie emitter–detector photoconductive antennas (PCAs) based on low-temperature grown-gallium arsenide (LTG-GaAs) thin-film devices on silicon-dioxide/silicon (SiO2/Si) host substrates for integrated terahertz (THz) systems. The LTG-GaAs thin-film devices are fabricated with standard photolithography and thermal evaporation of metal-contact layers of chromium (Cr), nickel (Ni) and gold (Au). They are etched selectively and separated from their growth GaAs substrate. The LTG-GaAs thin-film devices are then heterogeneously integrated on bow-tie antenna electrodes patterned on the surface of a SiO2/Si host substrate for THz emitters and THz detectors. Cost-effective and selective integration of LTG-GaAs thin-film devices on a Si platform is demonstrated. THz radiation from the fabricated THz PCAs is successfully measured using a pump–probe THz time-domain configuration. The THz temporal duration was measured at full width half maximum of 0.36 ps. Its frequency spectrum exhibits a broadband response with a peak resonant frequency of about 0.31 THz. The demonstration illustrates the feasibility of creating heterogeneously integrated THz systems using separately optimized LTG-GaAs devices and Si based electronics.